[Common prediction equations of respiratory function tests from children to adults in Japan].

In order to make common prediction equations of respiratory function tests (RFTs) from children to adults in Japan, we combined data of RFTs accumulated for "Reference values of spirogram and arterial blood gas levels in Japanese" reported in 2001 at the Japanese Respiratory Society congress and those for "An attempt to establish reference vales of respiratory function tests for Japanese children and adolescents" reported in 2006 from the Tohoku district. We then conducted multiple regression analysis on forced vital capacity, forced expiratory volume in 1 second (FEV1), V50, V25, and Gaensler's FEV1%, since they were measured under the same condition in the both reports. With all the combinations of 5 dependent variables (age, height, age2, height2, and age x height), multiple regression analysis was performed for each RFT. Judging by both evaluation indices of adjusted R-square and Mallows's Cp statistic, the equation using 4 dependent variables of age, height, age2, and age x height demonstrated roughly high efficiency for all RFTs. Therefore, we decided the equation excluding a dependent variable of height2 as common prediction equations for all RFTs and demonstrated the prediction equation for each RFT by sex.